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True experimental design
-manipulation of IV
Tx and Control group
-Random Assignment to treatment and control group to optimize equivalence
types of true experimental designs
the pretest-posttest control group design; the posttest-only control group design, Solomon 4-group, Factorial, Repeated measures
quasi-experimental design
An experiment that does not require random assignment to conditions, but can manipulate IV, Tx/Control,
Types of Quasi-Experimental Designs
nonequivalent pre-test posttest design, nonequivalent posttest only
methods to enhance equivalence if no random assignment?
-appropriate inclusion/exclusion criteria
-matching
-statistical control (ANCOVA)
-stat comparison of demographic characteristics/pertinent variables to determine if differences between groups exist at outset
non experimental design definition
describe relationships among variables of ONE group of subjects; random assignment NOT APPLICABLE
Types of non-experimental research
ex post facto/retrospective
descriptive correlational
time series design
survey research
outcomes research
secondary analysis, meta analysis, epidemiological, historical research
nonparametric testing data level
nominal/ordinal
chi square
Non parametric test used when you have nominal data; used to determine whether two distributions differ significantly; tests hypothesis about proportion of cases falling into various categories; computed by summing differences between observed and expected frequencies:
chi square example
is there a difference between males and females and smoking behavior?
Mann-Whitney U test
a nonparametric test used to compare two independent samples on an ordinal-level outcome variable that utilizes ranking (nonparametric t-test equivalence)
logistical regression
tests relationships between multiple IVs and a NOMINAL DV: probability of an event to occur
logistical regression example
do weight, height, and gender predict an MI (yes/no)?
multiple regression
to predict relationships: do multiple IVs predict a DV? (I/R level data)
multiple regression example
do hours of sleep, hours of studying, age, and gender predict scores on a research exam?
simple linear regression
regression analysis involving one independent variable and one dependent variable in which the relationship between the variables is approximated by a straight line
simple linear regression example
do number of daily calories consumed predict weight in lbs?
parametric test level of measurement
DV is at interval or ratio level
t-test
a parametric inferential statistical test that tests the differences in means between two groups (paired or independent) (I/R level)
ANOVA
compares the differences in means between 3 or more groups (I/R level)
factorial ANOVA
tests differences in means in 3+ groups: looks at main effects of IVs AND interaction effects of the IVs on the DVs. IV will have two levels.
factorial anova example
what is the impact of stress (high/low) and gender (M/F) on sleep quality? each is tested separately, and then interaction effect is also tested
independent t test
tests differences between two groups means of two independent groups (control vs treatment group)
independent t test example
is there a difference in systolic BP of patients who took drug X compared to placebo?
paired t test or t test for 2 dependent groups
tests differences between 2 groups means comparing means of the same group like pre test and post test, allowing within group and between group comparisons
paired t test example
is there a difference between pre test and posttest scores?
statistical power
calculation (specific stat test used in study) to determine a minimum number of subjects needed to detect treatment effect if present: especially pertinent if no differences or effects were found: established SAMPLE SIZE ADEQUACY
tests for VALIDITY
content, construct, criterion, and face
content validity
panel of experts
construct validity
factor analysis
criterion validity
compare scores with another instrument measuring same concept (+ correlation) OR compare scores with another instrument that measures an opposite concept (- correlation)
face validity
readability, enough white space
types of reliability
test-retest
inter-rater
internal consistency
internal consistency
cronbach's alpha: .80 for established instruments, .70 for new instruments. pertinent to report in any PSYCHOSOCIAL instrument being used to quantify a single concept
test-retest reliability
relevant to report in longitudinal studies with repeated use of the instrument over time with values that are not likely to change (ex. not mood). minimum is .75
interrater reliability
compares scores of multiple raters using the same instrument who observe the same event (only pertinent in observational studies): minimum adequacy: .75
biophysical measures: validity and reliability
INHERENTLY VALID, only reliability is applicable. Ex: calibration done? Consistent training documented?
internal validity threats defined
related to strength of design and the degree of control to better isolate effects of IV on DV and rule out competing or alternative explanations
selection threat
no random assignment; results in bias from preexisting differences between groups (nonequivalence)
mortality
loss of subjects during a study (differential dropout/attrition is problematic)
history
occurrence of events concurrent with IV that may have affected the DV
maturation
process occurring as a result of time: participants grow older, wiser, or stronger as time goes on, rather than occurring due to the IV (esp. a problem in pediatric research)
testing threat
a threat to internal validity produced by a previous administration of the same test or other measure
instrumentation threat
Reliability and validity problems with psychosocial measures used, lack of training, consistent procedures/calibration issues
statistical regression threat
subjects classified in groups based on pretest; extremes allow drifting to means by chance in posttest
diffusion/imitation of treatment/contamination
treatment and control groups communicate with each other and intermingle
resentful demoralization
reaction of control or no treatment group which may alter true response or cause dropout
experimental expectancy effect
subjects behave how they believe the researcher wants, either purposely or subconsciously
experimenter expectancy/bias
researchers bias results with what they hope to find; especially a risk if data collectors are not blinded
Hawthorne effect
a positive effect observed in patient because they are being paid attention to
novelty effect
reaction to newness of intervention/ treatment rather than its intrinsic value
placebo effect
expectations about benefit of treatment independent of actual intervention; situational contaminants, treatment not administered under same circumstance (homogeneity of procedures), or inconsistent application of treatment (ignore this whole card its placebo)
external validity is related to...
SAMPLING: if subjects not recruited into the study in a random way, then the results CANNOT be generalized beyond the sample/setting
simple random sampling
every subject has equal and independent chance of being chosen to participate
techniques: pick out of a hat, random numbers table, computer-generated table
time consuming, but maximizes representativeness
stratified random sampling
A form of probability sampling; a random sampling technique in which the researcher identifies particular demographic categories of interest and then randomly selects individuals within each category; age, gender, ethnicity. ex: 900 nurse practitioners stratified by practice specialties
cluster sampling
GROUPS, not INDIVIDUALS are randomly selected to be in a study. Ex: nurses randomly selected ICU and nonICU units from 16 randomly selected hospitals in the Netherlands
systematic sampling
every nth item in the population is selected
convenience sampling
using a sample of people who are readily available to participate; non probability
quota sampling
A nonprobability sampling technique in which researchers divide the population into groups and then arbitrarily choose participants from each group; example: 100 nursing home residents in the county, 25 from each of the 4 nursing homes
convenience with snowball/network
relies on subjects that identify others with similar characteristics, or obtained via social networking
purposive sampling
selecting sample members to study because they possess attributes important to understanding the research topic; HAND PICKED common in QL studies
what are some of the potential culprits when no results are found?
SMALL SAMPLE SIZE: no power analysis done a priori or post hoc, min. "n" not met. treatment effects or relationships were there but could not be detected because outliers are more likely to skew the results
WEAK INSTRUMENTS: poor R and V of psychosocial instruments OR problems with biophysical measures leading to inaccurate data
WEAK DESIGN/METHOD: no control/comparison group; tx not applied consistently, constancy or conditions
IV THREATS: can distort or equalize tx effects
what determines a study's generalizability/external validity?
method of sampling (random vs. nonrandom)
what does determining a minimum # of subjects via power analysis do for a study?
tells the "power" to detect tx effects or relationships between variables
what does random assignment to treatment and control do for a study?
ensures EQUIVALENCE and internal validity
what threat is associated with quasi experimental design?
selection threat if random assignment not being done
evidence-based practice
nursing care provided that is supported by sound scientific rationale and the best available scientific evidence
what does EBP de-emphasize
ritual, isolated and unsystematic clinical experiences, ungrounded opinions and tradition as the basis for practice
characteristics of EBP
-Problem-solving approach that considers clinical experience
-Combines research evidence, knowledge, and theory
what is research utilization?
process by which knowledge generated from research becomes incorporated into clinical practice; involves applying research to improve patient outcomes, and addresses RESEARCH-PRACTICE GAP
research practice gap
emerges when there are differences between clinical practice and the research on effective clinical practice; nurses must expedite closing the research practice gap in order to make dramatic, needed improvements to our healthcare delivery system
reasons for delay in practice or utilization of new research
nurse unaware of findings, nurse lacks skill of locating/understanding research, lack of dialogue between researchers and clinicians, research reported in statistics vs clinically meaningful terms, nurses reticent to accept and implement innovations or change in practice
Steps of Evidence Based Practice
selecting a topic, asking a clinical question (PICOT), forming a team, ROL, tracking down best evidence, developing a search strategy, appraising evidence critically, (hierarchy of evidence?)
EBP: selecting a topic
knowledge focused triggers: ideas generated when staff read/listen to scientific papers at conferences
background questions: who, what, where, when, why
foreground questions: specific knowledge to inform clinical decisions (PICOT)
EBP: asking a clinical question
P: patient population
I: Intervention/issue of interest
C: comparison of interest (usually standard of care)
O: outcome of interest
T: time frame (may not always apply)
EBP: forming a team
selecting appropriate members who have stake in the delivery of care and are familiar with the problem; optimally will be interdisciplinary
EBP systematic review
the consolidation of research evidence that incorporates a critical assessment and evaluation of the research and addresses a focused clinical question using methods designed to reduce the likelihood of bias
EBP: tracking down best evidence and developing search strategy
literature search: start broad by identifying journals of interest first using electronic databases (CINAHL, MEDLINE, PubMed, Cochrane Library). Then develop inclusion/excl criteria that you want to include; using Boolean operators in search (and, or, not)
PRISMA
Evidence based minimum set of items for reporting in systematic reviews and meta-analysis
Focuses on the reporting of reviews evaluating randomized trials, but can also be used as a basis for reporting systematic reviews of other types of research, particularly evaluations of interventions
grey literature
unpublished evidence that has not been included in databases frequently seen in commercial or academic publishing. NOT peer reviewed, challenging to find
Hierarchy of Evidence
BEST: Systematic review or meta analysis of randomized controlled trials (RCTs) and evidence based clinical practice guidelines
2. One well designed RCT
3. Quasi-experimental study wo randomization
4. Well designed case-control and cohort studies
5. Systematic reviews of descriptive and/or qualitative studies
6. Single descriptive and/or qualitative studies
WORST: Expert opinion/expert committee reports.
ethical concerns with EBP
ALWAYS SHARE INFO THAT WAS FOUND: type of support from evidence, benefits likely to be realized, separation of likely adverse outcomes from uncommon events